The 17-time grand slam champion came into the Australian Open as an outsider after his 2013 struggles but has looked back to something like his best form in wins over Jo-Wilfried Tsonga and Andy Murray.

Having lost to Murray in the semi-finals 12 months ago, Federer took revenge to reach the last four in Melbourne for an 11th consecutive time.

The 32-year-old has not made a grand slam final since winning the last of his titles with victory over Murray at Wimbledon in 2012.

He has beaten Nadal only 10 times in 32 meetings, and not at a slam since the Wimbledon final of 2007, but the Spaniard is struggling with a blister on the palm of his left hand and battled past Grigor Dimitrov in his quarter-final.

For Federer, meanwhile, there is also the tantalising possibility of an all-Swiss final, with Stanislas Wawrinka due to play Tomas Berdych on Thursday after his stunning upset of Novak Djokovic.

"For me it's an amazing result to be in the semis," said Federer. "This one feels different because of the tougher times I've had in the slams.

"Plus what I really love is another Swiss is in the semis as well. It's the first time in history. So that's a big deal.

"I didn't think about it all the time when I was playing, but it was definitely inspiring tennis by him. For me, it's as well a dream run, and I hope I can keep it up against Rafa.

"Clearly when you're in the semis, you start dreaming. There's no doubt about that."

Federer will hope the changes he has made can bring about a change of fortune against Nadal.

The Swiss is playing with a larger-headed racquet and has Stefan Edberg in his corner to advise him and regular coach Severin Luthi.

Edberg has already won the battle of the super coaches, with Murray's mentor Ivan Lendl and Djokovic's new head coach Boris Becker both heading home.

Federer will face Nadal at a slam for the first time since the semi-finals here two years ago, and he said: "He's been tough to play against, no doubt. I'm happy I get a chance to play him in a slam again.

"The head-to-head record is in his favour. I'm looking forward to speaking to Stefan, because when we spoke together when he came to Dubai and we spoke about the game, we clearly spoke about playing Rafa, as well. He thought he had some good ideas."

Nadal had to fight back from a set down against first-time slam quarter-finalist Dimitrov and admitted he was "so lucky" not to drop the third as well.

Dimitrov had three set points and on the second he pushed a routine forehand wide, with Nadal eventually coming through 3-6 7-6 (7/3) 7-6 (9/7) 6-2.

The world number one was a long way from his best form throughout and conceded the strapping on his blister is badly affecting his serve.

"I feel that with the tape I can lose the racquet when I'm serving," said Nadal. "That's a terrible feeling for a serve.

"I served slower, I served bad. But I was able to win a match against a very difficult opponent, so that has much more value than when everything is great.

"And because of these victories, sometimes it happens that the next day you are able to play much better.

"I'm going to try to improve. If not, I'm not going to have the chance to be in the final."

This has been a breakthrough grand slam for 22-year-old Dimitrov, but the Bulgarian knew he had let a great chance slip through his fingers, and he fought back tears as he discussed the missed forehand.

He said: "I'm a bit shattered. It's tough losing that match. I came out expecting nothing less than to win.

"Of course I shed a few tears, but it should hurt. And it does hurt.

"Once you take a decision, never look back. It's the same thing in life: you make mistakes. It's in the past.

"I'm sure I could have done something different. But in a match everything comes down to a split second. It's whether it's in or out."

Wawrinka and Berdych have both made it through to the semi-finals in Melbourne for the first time.

Federer is a close friend and supporter of Wawrinka, and he said of Tuesday night's match: "At the end I was standing up, hands in the air like him.

"When he wins big points, you do fist pump. I high five with Mirka. We watched the entire fifth set together. It was amazing."